PRESIDENT’S ADDRESS. 49] 
the study of vital processes by such means, It is quite true that 
the chemistry and physics of to-day are totally unable to throw 
any ray of light upon such biological phenomena as growth and 
heredity, and it may appear sanguine to imagine that the chemistry 
of the future ever will do so. 
The great and fundamental distinction between the growth of 
an unorganised body and a living cell is that whereas a crystal of 
any definite substance can only grow by the aggregation of similar 
molecules of the same substance, in the growth of a cell the cell 
draws upon totally dissimilar molecules, and by some unknown 
property converts them into molecules of similar constitution to 
itself. The living cell, in fact, possesses the power of assimila- 
tion, which is the fundamental distinguishing characteristic from 
all that is not living. 
It is well, however, to remember that not very many years ago 
the belief in the impossibility of synthesising organic bodies, such 
as urea and sugars, was universal, and the formation of these 
bodies was supposed to necessitate the operation of ‘“ vital force.” 
Wohler showed how easily urea may be built up from its elements, 
and the fine work of the brothers Fischer has demonstrated not 
only the possibility of manufacturing the various sugars in the 
laboratory, but also some suggestive insight into the probable 
details of the synthesis of car bohydrates by. pants. 
Professor Foster, i in his British Association address at Toronto, 
1897, reproached the chemists for having lagged behind in attacking 
just those chemical problems, some light upon which would be so 
gratefully received by their phy siological brethren. Would that 
the chemists would assist us in understanding the chemical proper- 
ties of proteids and other bodies possessed of huge molecular weight, 
or provide us with a chemical interpretation of the details of the 
action of ferments. But the chemists are loath to undertake the 
investigation of substances which they cannot crystallise or even 
prepare in a pure condition, and of which they cannot ascertain 
the molecular weight. For this we cannot blame them. I think 
they are finding the interpretation of chemical relationships suff- 
ciently complex even among bodies with which they can start upon 
so sure a basis, and are wise in confining their attention for the 
present to problems which they can attack upon general chemical 
principles. Meanwhile, the chemical investigations of essential 
importance to biologists have, in spite of their inexactitude, of 
necessity been taken up by physiologists. 
During recent years, however, larger numbers of physiologists, 
and among them some of the best, have been devoting their atten- 
tion to the elementary phenomena exhibited by cellular activity. 
Acting upon the conviction that these are essentially identical in 
all cells, Engelmann, Budimann, Verworn, Loeb, and a host of 
others have been attacking problems of cellular physiology by 
